But Nobel Prize winners Perlmutter, Riess and Schmidt don’t need worry about being short of cash anymore. They can forget eating instant noodles and cobbling together loose change to keep the electricity meter running. Winning the highest accolade in science is more than luck. It wasn’t their lucky stars that bagged them the $1.5 million Prize this week; but their tenacity in studying celestial bodies.

Their discovery – that the Universe is expanding at an ever increasing speed – is simply profound. Although they first discovered it back in 1998, it still causes confusion amongst bespeckled star-gazers and flies in the face of the accepted notion that everything around us is simply the result of a Big Explosion.

No one has yet come up with a wholly convincing reason why stars are speeding away from each other at an increasing rate of knots. I have a little theory that’s been on my mind for a while – and I’d like to share it. Watch out, things are going to get rather theoretical…

Are we in the Dark?

Don’t get me wrong, I know I’m straying from my field of expertise; physics A-levels were over a decade ago and astrophysics didn’t feature highly at medical school. However, I feel reasonably well acquainted with science-y goings-on (for a medic and health science lecturer that is) – so here goes:

No one likes being in the dark – least of all scientists. However I have a problem with the modern explanations for heavenly mysteries: They seem to rely on ‘dark’ a lot. Dark matter – the presumed vast quantities of invisible mass lurking out there somewhere – is the accepted theory for a discrepancy between gravitational laws and astronomer’s observations. Similarly, dark energy – an unknown, unmeasured and unseen force – is apparently the thing that is spreading the Universe apart at ever increasing speeds.

Professor Hawking would have me for breakfast in a debate about this, but as far as I can see there isn’t a great deal of evidence to support these ideas and it all sounds a bit, well, mythical.

A Lighter Alternative

Just how constant is light?

Rather than Dark Energy pushing stars and galaxies apart – like some ethereal being blowing into the balloon of the Cosmos – my (wholly speculative) idea relies on the speed of light. I’ve looked for this theory elsewhere, but haven’t found it written down as a reason for the accelerating expanding universe (perhaps there’s a reason for that?)

What if the speed of light at the far reaches of the Universe was different to our own – and this difference is causing the illusion of an accelerating expanding universe?

To suggest that the speed of light is not constant, tramples on Einstein’s grave and risks a paramilitary uprising in the Large Hadron Collider canteen. That said, there is some evidence to suggest the sacred ‘c’ (in e = mc2) – the speed of light in a vacuum – may not be as steadfastly unchanging as we believe. Even before Italians starting saying that their Neutrinos were going faster than the speed of light, Australians last year reported that they had evidence that the speed of light may be different in different parts of the Universe.

Just supposing that the speed of light were faster in our district of the Milky Way than elsewhere – couldn’t that explain why far galaxies appear to be speeding away. Like seeing the optical illusion of a straw bend as it enters a glass of water – could the appearance of an accelerating universe just be an optical illusion?

“Is there an astrophysicist in the House?”

I know on occasion, a physicist passes by my humble blog – and I would love to be set straight by a more proficient cosmologist than I!

Failing that, would someone kindly go on and prove my theory – and could I please have a share in the Nobel Prize when you win…?

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The idea that the speed of light could vary with time has been around for a long time, at least since the time of Dirac in the 1930s. A time-varying speed of light is a sometimes-discussed alternative to cosmic inflation, and under the right circumstances, I suppose it could mimic dark energy as well.

However, our observations of relics from the early Universe, in particular the cosmic microwave background (when the Universe was only 0.003% of its current age) and the abundance of the light elements (from when the Universe was less that four minutes old) place great constraints on how much the speed of light could have varied in that time.

In particular, this paper: http://cdsweb.cern.ch/record/421743/files/0001292.ps.gz shows that from the cosmic microwave background until today, the maximum allowed variation in the speed of light’s value is just 4%! So it’s a fun idea to think about, but the constraints make it rather unsuitable for explaining dark energy.

Hi Dr. Stu,
A modern discussion of inflation theory would not be complete without a reference to the “open inflation” theory that posits the presence of a scalar field know as an ‘inflaton’. While a nascent idea, it is a provocative concept that, along with ‘eternal inflation’, posits that our universe is a ‘bubble’ that’s isolated by the super-luminal expansion of the space around us- said expansion being driven by the inflaton. For more about this theory, Anthony Aguirre at the University of California at Santa Cruz is an eloquent proponent of this idea. His page is at http://scipp.ucsc.edu/~aguirre/Home.html

Wow – that’s heavy stuff. I know that multiple universe theory seems to be ‘in vogue’ at the moment to try to answer some of the big questions. What I find fascinating is that these ideas (like those on Aguirre’s site) seem to be unfalsifiable – they cannot be proven or disproven empirically.

Correct me please, but it appears that philosophy and science seem to be rather closely intertwined when the limits of our understanding are reached. It’s all very intriguing (for a medic and generalist) to try and get one’s head around.

I guess that should Higgs boson, fail to be found – the potential flood gates for serious ‘outside the box’ thinking will be opened?!

We know expansion is accelerating because the farther an object is’ the faster it seems to be moving away from us. Doesn’t that mean expansion is slowing down? The furthest objects are also the earliest so they’d be closer to the big bang. Faster billions of years ago means slower now doesn’t it? Sorry if this just dumb.